I cant quite get cloth sawing down on my character
The simulation looks good, it just needs a few tweaks.

Fix the arms first ;-) The sleeves can collide and get messed up there. Either rotate them in Edit mode or use the Pose Brush in Sculpt mode (increase the brush size)
In Object mode apply the scale to the shirt (Ctrl+A)
In Edit mode, select the whole mesh the shirt (A), then flip normals (Alt+N) because your shirt is turned inside out
In Edit mode, scale the shirt a bit up (~20%) because you need more fabric to wrap around the body
Move the shirt closer to the body by scaling it down along the X-axis (S, then X). Make sure the threads to not intersect with the body.
In the Cloth settings, reduce the distance for Object Collision and in Self Collision to 0.005 m. If Self Collision is too low the mesh can 'explode', if Object Collision it's too high the fabric starts to 'crawl' and flips over the head.
Start the simulation. It should look good after 15-20 frames. If not, cancel it, and tweak the settings or try another start position for the shirt.
The seams might have some gaps. I could not find out why this is so. And there can be rough wrinkles. But you can fix this after you applied the cloth modifier.
If you're happy with the result duplicate the shirt (D) in Object mode to create a backup object.
Apply the Cloth modifier in the drop-down menu on the Modifier panel.
To remove the gaps switch to Edit mode, select everything, and do a Merge By Distance (M, 0.017 m). You can adjust the distance in the dialog that appears (F9 brings it back if you missed it). Have a look under the arms if they are all gone.
To smooth the rough wrinkles on the shoulder switch to Sculpt mode, use the Smooth brush with a strength of 0.2 and smooth it. The Inflate brush can be used to bring the volume back if you have smoothed too much. (The Cloth brush can be used to add more wrinkles. Use a Subdivision modifier is needed.)
Congratulations! You have made it! The simulation is a bit choppy. Small changes in the values can have big effects and it usually takes several attempts to get a good result.


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